A calibrated potentiometer is used to measure the e.m.f. of a cell because the
Ainternal resistance of a cell is small compared with that of the potentiometer
Bpotentiometer has a linear scale
Cpotentiometer takes no current from the cell
Dresistance of the potentiometer is less than that of a voltmeter
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Question 972
jamb1989
Three resistors, with substances 250\(\Omega\), 500\(\Omega\) and 1k\(\Omega\) are connected in series. A 6V battery is connected to either end of the combination. Calculate the pot3ential difference between the end of the 250\(\Omega\) resistor.
A0.20V
B0.86V
C1.71V
D3.43V
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Question 973
jamb1989
The resistance of a 5m uniform wire of cross-sectional area 0.2 x 10-6m2 is 0.425. What is the resistivity of the material of the wire?
A1.10 x 10-6\(\Omega\)m
B4.25 x 10-6\(\Omega\)m
C2.40 x 10-7\(\Omega\)m
D1.70 x 10-8\(\Omega\)m
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Question 974
jamb1989
A bar magnet is most effectively demagnetized by
Aplacing it in a N - S position and hitting it with a hammer
Bsubjecting it to an electric current from a battery
Cbringing its north pole in contact with the north pole of a very strong magnet
Dheating the magnet
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Question 975
jamb1989
When a number of identical small magnets are arranged in a line, the strength of the resultant magnet
Aia largest when they are arranged end to end
Bis greatest when they are arrangedparallel with like poles adjacent to each other
Cdepends only on the number of magnets provided they arev parallel
Dis greater when the magnets are arranged on a wooden surface than on a metaln surface
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Question 976
jamb1989
Two insulated charged spheres of different sizes and carrying opposite charges are connected together by a metallic conductor. Current will flow from one sphere to the other until both sphere
Acarry the same magnitude and sign of charge
Bare at the same potential
Care at the same temperature
Dare of the same size
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Question 977
jamb1989
Which of the following pairs is NOT part of the electromagnetic spectrum? i. Radio waves. ii. Beta rays. iii. Gamma rays. iv. Alpha rays
Ai and ii
Biii and iv
Ci and ii
Dii and iv
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Question 978
jamb1989
Dispersion of light by a glass prism is due to the
Adifferent colours of the glass
Bdifferent speeds of the various colours in glass
Cdefects in the glass
Dhigh density of glass
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Question 979
jamb1989
When a yellow card is observed through a blue glass, the card would appear.
Ablack
Bgreen
Cred
Dwhite
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Question 980
jamb1989
A far sighted person cannot see objects that are less than 100cm away. If this person wants to read a book at 25cm, what type and focal length of lens does he need?
Aconvex, 20cm
Bconcave, 20cm
Cconvex, 33cm
Dconcave, 33cm
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Question 981
jamb1989
The plane mirrors in a kaleidoscope are usually placed
Aat an angle of 60o
Bparallel to one another
Cperpendicular to one another
Dat an angle of 45o
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Question 982
jamb1989
The magnification of the image of an object placed in front of a convex mirror is \(\frac{1}{3}\). If the radius of curvature of the mirror is 24cm, what is the distance between its object and its image?
A8cm
B16cm
C24cm
D32cm
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Question 983
jamb1989
Light of wavelength 5000 x 10-8cm travels in free space with a velocity of 3 x 108ms-1. What is its wavelength in glass of refractive index 1.5?
A3333 x 10-8cm
B5000 x 10-8cm
C6666 x10-8cm
D750010-8cm
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Question 984
jamb1989
In a sound wave in air, the adjacent rarefactions and compressions are separated by a distance of 17cm. If the velocity of the sound wave is 340ms-1. Determine the frequency
A10Hz
B20Hz
C1000Hz
D5780Hz
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Question 985
jamb1989
When the tension in a sonometer wire is doubled, the ratio of the new frequency to the initial frequency is?
A\(\frac{1}{\sqrt2}\)
B\(\frac{1}{2}\)
C\(\sqrt2\)
D2
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Question 986
jamb1989
A vibrator of frequency 60Hz is used in generating transverse stationary waves in a long thin wire, If the average distance between successive nodes on the wire is 45cm, find the speed of the transverse waves in the wire.
A27ms-1
B54ms-1
C90ms-1
D108ms-1
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Question 987
jamb1989
From the kinetic theory of gases, temperature is a
Aform of energy and is proportional to the total kinetic energy of the molecules
Bform of energy and is proportional to the average kinetic energy of the molecules
Cphysical property and is proportional to the total kinetic energy of the molecules
Dphysical property and is proportional to the average kinetic energy of the molecules
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Question 988
jamb1989
An electric heater is used to melt a block of ice of mass 1.5kg. If the heater is powered by a 12V battery and a current of 20A flows through the coil, calculate the time taken to melt the block of ice at 0oC. [specific latent heat of fusion of ice = 336 x 103Jkg-1]
A76.0min
B35.0min
C21.0min
D2.9min
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Question 989
jamb1989
A mass of gas at 7oC and 70cm of mercury has a volume of 1200cm3. Determine its volume at 27oC and pressure of 75cm of mercury.
A1200cm3
B1378cm3
C4320cm3
D4629cm3
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Question 990
jamb1989
A column of air 10.0cm long is trapped in a tube at 27oC. What is the length of the volume at 100oC?
